Video: polish aspect ratio related code comments to make it clearer

Source/Core/Core/HW/VideoInterface.cpp

@@ -477,7 +477,7 @@ float VideoInterfaceManager::GetAspectRatio() const
   // signal (which would be 4:3)
 
   // This function only deals with standard aspect ratios. For widescreen aspect ratios,
-  // multiply the result by 1.33333..
+  // multiply the result by 1.33333... (the ratio between 16:9 and 4:3)
 
   // 1. Get our active area in BT.601 samples (more or less pixels)
   int active_lines = m_vertical_timing_register.ACV;

Source/Core/Core/HW/VideoInterface.h

@@ -388,9 +388,9 @@ public:
   u32 GetTicksPerHalfLine() const;
   u32 GetTicksPerField() const;
 
-  // Get the aspect ratio of VI's active area.
+  // Get the aspect ratio of VI's active area (rarely matching pure 4:3).
   // This function only deals with standard aspect ratios. For widescreen aspect ratios, multiply
-  // the result by 1.33333..
+  // the result by 1.33333... (the ratio between 16:9 and 4:3)
   float GetAspectRatio() const;
 
   // Create a fake VI mode for a fifolog

Source/Core/DolphinQt/Config/Graphics/EnhancementsWidget.cpp

@@ -561,12 +561,11 @@ void EnhancementsWidget::AddDescriptions()
       "causes slowdowns or graphical issues.<br><br><dolphin_emphasis>If unsure, leave "
       "this unchecked.</dolphin_emphasis>");
   static const char TR_WIDESCREEN_HACK_DESCRIPTION[] = QT_TR_NOOP(
-      "Forces the game to output graphics for any aspect ratio. Use with \"Aspect Ratio\" set to "
-      "\"Force 16:9\" to force 4:3-only games to run at 16:9.<br><br>Rarely produces good "
-      "results and "
-      "often partially breaks graphics and game UIs. Unnecessary (and detrimental) if using any "
-      "AR/Gecko-code widescreen patches.<br><br><dolphin_emphasis>If unsure, leave "
-      "this unchecked.</dolphin_emphasis>");
+      "Forces the game to output graphics at any aspect ratio by expanding the view frustum "
+      "without stretching the image.<br>This is a hack, and its results will vary widely game "
+      "to game (it often causes the UI to stretch).<br>"
+      "Game-specific AR/Gecko-code aspect ratio patches are preferable over this if available."
+      "<br><br><dolphin_emphasis>If unsure, leave this unchecked.</dolphin_emphasis>");
   static const char TR_REMOVE_FOG_DESCRIPTION[] =
       QT_TR_NOOP("Makes distant objects more visible by removing fog, thus increasing the overall "
                  "detail.<br><br>Disabling fog will break some games which rely on proper fog "

Source/Core/VideoCommon/Present.h

@@ -46,7 +46,7 @@ public:
 
   void ConfigChanged(u32 changed_bits);
 
-  // Display resolution
+  // Window resolution (display resolution if fullscreen)
   int GetBackbufferWidth() const { return m_backbuffer_width; }
   int GetBackbufferHeight() const { return m_backbuffer_height; }
   float GetBackbufferScale() const { return m_backbuffer_scale; }
@@ -58,6 +58,7 @@ public:
 
   void UpdateDrawRectangle();
 
+  // Returns the target aspect ratio the XFB output should be drawn with.
   float CalculateDrawAspectRatio(bool allow_stretch = true) const;
 
   // Crops the target rectangle to the framebuffer dimensions, reducing the size of the source
@@ -126,6 +127,9 @@ private:
   Common::Flag m_surface_changed;
   Common::Flag m_surface_resized;
 
+  // The presentation rectangle.
+  // Width and height correspond to the final output resolution.
+  // Offsets imply black borders (if the window aspect ratio doesn't match the game's one).
   MathUtil::Rectangle<int> m_target_rectangle = {};
 
   RcTcacheEntry m_xfb_entry;

Source/Core/VideoCommon/VertexManagerBase.cpp

@@ -91,8 +91,9 @@ static bool IsAnamorphicProjection(const Projection::Raw& projection, const View
                                    const VideoConfig& config)
 {
   // If ratio between our projection and viewport aspect ratios is similar to 16:9 / 4:3
-  // we have an anamorphic projection. This value can be overridden
-  // by a GameINI.
+  // we have an anamorphic projection. This value can be overridden by a GameINI.
+  // Game cheats that change the aspect ratio to natively unsupported ones
+  // won't be automatically recognized here.
 
   return std::abs(CalculateProjectionViewportRatio(projection, viewport) -
                   config.widescreen_heuristic_widescreen_ratio) <

Source/Core/VideoCommon/Widescreen.cpp

@@ -53,6 +53,7 @@ void WidescreenManager::Update()
 }
 
 // Heuristic to detect if a GameCube game is in 16:9 anamorphic widescreen mode.
+// Cheats that change the game aspect ratio to natively unsupported ones won't be recognized here.
 void WidescreenManager::UpdateWidescreenHeuristic()
 {
   const auto flush_statistics = g_vertex_manager->ResetFlushAspectRatioCount();

Source/Core/VideoCommon/Widescreen.h

@@ -11,11 +11,14 @@
 class PointerWrap;
 
 // This class is responsible for tracking the game's aspect ratio.
+// This exclusively supports 4:3 or 16:9 detection by default.
 class WidescreenManager
 {
 public:
   WidescreenManager();
 
+  // Just a helper to tell whether the game seems to be running in widescreen,
+  // or if it's being forced to.
   bool IsGameWidescreen() const { return m_is_game_widescreen; }
 
   void DoState(PointerWrap& p);